Trimatic Automatic Transmission

Extract from HQ Holden Service Manual Part No: M37017

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INTRODUCTION:   This section covers aspects of the HQ Trimatic Automatic Transmission which differ from or are not covered in the Trimatic Shop Manual P/N M36751. This section must therefore be used in conjunction with the Shop Manual when servicing the Trimatic transmission in HQ series vehicles.

GENERAL DESCRIPTION:   The three speed Trimatic Automatic Transinission which is standard equipment on the Statesman De Ville and available as an option on other HQ models except with the 350 cu. in. engine. replaces the conventional clutch and transmission. The Trimatic is a fully automatic transmission utilizing a hydraulic torque converter and a compound planetary gear set with three multi disc clutches and a single band enclosed in an aluminium alloy case. Upshffts and downshifts are controlled by road speed, engine vacuum and a solenoid controlled detent valve within the transmission. The transmission fluid is cooled in a heat exchange unit situated in the lower tank of the engine radiator, metal tubes connect the cooler with the transmission.

OPERATING RANGES:   The control for the Trimatic transmission is provided by either a selector lever mounted on the steering column or a selector lever mounted to the floor panel and protruding through a console. The Monaro GTS model is available only with floor mounted selector lever. The selector indicator has six positions in the following order;

  • L - holds transmission in 1st gear, prevents upshifting
  • S - permits 1 - 2 upshifting
  • D - permits 1 - 2 - 3 upshifting
  • N - Neutral - no drive
  • R - Reverse
  • Park

Selection of the appropriate operating range is obtained by moving the selector lever until the required range is indicated. For safety a Neutral safety switch is included in the starter motor solenoid circuit. This ensures that the starter motor can only be operated when the selector lever is in the 'PARK' or 'N' position. The steering column Mounted selector lever must be moved through a gate to select either Park. R. L. or S while a button on the 'T' handle of the floor shift lever must he depressed before these ranges can be selected.

TOWING:   All Trimatic equipped vehicles can be towed without disconnecting the propeller shaft except in cases of transmission, rear axle or propeller shaft failure. With the propeller shaft connected, the vehicle can be towed at speeds up to 30 m.p.h. (approximately 50km/h) for distances up to 30 miles (approximately 50 km) with the selector lever in the 'N' position.

TRANSMISSION CODES:   The transmission identification plate (Fig. 1) carries the transmission serial number and application code. The following codes are used for HQ production transmissions with both floor and column shift and all axle and tyre combinations.

CODE
ENGINE SIZE (CU. IN.)
HN
173
HT
202
HO
253
HP
308

MAINTENANCE:

Recommended Lubricant:
   The Trimatic automatic transmission requires a special lubricant which has been especially formulated and tested and is available from all Dealers. Fluid bearing the name 'DEXRON' together with an identification number is recommended and should be used.

Checking Transmission Fluid Level:   The transmission fluid level should be checked every 6.000 miles or 3 months. It is essential that the correct fluid level is maintained.

NOTE: It is always good policy to check transmssion fluid level whenever engine oil level is checked.

The fluid level indicator is housed in the filler tube located at the right side rear of the engine. The vehicle must be on a level surface and the transmission should be at normal operating temperature.

NOTE: If the transmission fluid is not at operating temperature (approximatelv 180F - 190F) the correct temperature can be reached by driving the vehicle several miles, making frequent starts and stops.

Select 'Park' and allow the engine to idle for two minutes. With the engine still idling in 'Park' remove and wipe the level indicator with a clean non-fluffy rag or paper, insert and withdraw inmediately. If the level is low at normal operating temperature top up with 'DEXRON' Automatic Transmission Fluid to bring the level to the Full mark. Use a clean funnel with a fine mesh gauze filter. Do NOT overfill.

Cold Fluid Level Check:   The "FULL" mark on the fluid level indicator represents the correct level for a transmission at operating temperature with the engine idling and Park range selected. However, it is not always possible to adequately warm the transmission fluid in a workshop to accurately check the level prior to road test.

Should the level have to be checked cold. e.g. after transmission replacement or repair, the following procedure is recommended to allow for the considerable expansion that will occur as the ftuid temperature increases.

  1. With the vehicle on level ground, start the engine and move the selector lever through each range to fill the transmission internal passages.
  2. With the transmission in PARK range and the engine idling, add sufficient fluid to bring the level to the "add one pint" mark on the level indicator.
  3. After the transmission has been thoroughly warmed, the level must be rechecked with the engine idling and PARK selected. With warm fluid the level should be at the FULL mark on the indicator.

Draining and Refilling:   It is recommended that the Dexron Fluid be changed every 24.000 miles or 24 months. whichever occurs first for vehicles operating under normal service conditions and 12.000 miles or 12 months. whichever occurs first, for vehicles operating in heavy duty applications (taxi work, frequent trailer towing. etc.).

This recommendation applies only when "DEXRON" Automatic Transmission fluid is used. Other Fluids should not be used.

Periodic Band Adjustment:   It is recommended that the low band adjustment be checked and corrected if necessary at the same time or mileage as the fluid is changed. i.e. 24.000 miles / 24 months or 12.000 miles / 12 months. Band adjustment will necessitate removing the oil pan and servo cover and the opportunity should be taken to clean any accumulation of worn friction rnaterial, etc. from the pan cover and oil strainer.

  1. Raise the vehicle on a hoist or place on jack stands.
  2. Remove the drain plug from the oil pan and allow the oil to drain into a container.
    CAUTION: After a Iong run the oil will be hot enough to cause serious burns, therefore, suitable precautions must he taken.
  3. Remove the oil pan attaching bolts and oil pan.
  4. Remove the servo cover attaching bolts and servo cover.
  5. Adjust the low band as follows:-
    1. Using a 1/2 inch A/F open end spanner, hold the servo piston adjusting sleeve and loosen the lock-nut several turns.
    2. Using tool No. 7AT4 and an inch pound torque wrench, tighten the servo piston adjusting screw to 40 lbs. inches then back off the adjusting screw exactly four turns.
      IMPORTANT: The four turns back off is not an approxmate figure - it must he exact. If there is any evidence of excessive tightness of the adjusting screw in the sleeve, remove the screw and apply rod from the sleeve and examine the threads for damage. Replace the screw or free up the thread as required. Re-install the apply rod and screw and adjust band as descrihed previous
    3. Using Tool No. 7AT4 hold the adjusting screw firmly, hold the sleeve with a 1/2 inch A/F open end spanner and tighten the lock-nut to 12-15 lbs. ft. torque.
  6. Remove the three oil strainer attaching bolts and the strainer, discard the strainer gasket.
  7. Wash strainer in solvent and dry with compressed air.
  8. Reinstall strainer with a new gasket and tighten attaching bolts to 130 to 150 lbs. inches torque.
  9. Reinstall servo cover and oil pan using new gaskets and tighten cover bolts to 16-18 lbs. ft. torque and oil pan bolts to 6 to 9 lbs. ft. Install and tighten oil pan drain plug.
  10. Refill the transmission with 4 pints of "DEXRON" Automatic Transmission fluid. Start engine and check the level as outlined under the heading "Cold Fluid Level Check".
  11. Recheck level when transmission is at operating temperature.

SERVICE ADJUSTMENTS:

Neutral Start and Back Up Switch Adjustment:
   To prevent accidental engagement of the starter motor whilst the transmission is in a driving range. a Neutral Start switch is incorporated in the starter motor solenoid circuit. Vehicles equipped with steering column mounted selector lever have the switch mounted on the steering column jacket under the instrument panel. Vehicles equipped with the floor mounted selector lever have the switch incorporated with the floor mounted selector mechanism. Either one of these combinations ensures that the starter motor is only operative when the selector lever is in the 'Park' or 'N' position. A back-up lamp switch is also incorporated in the switch body. Before attempting to adjust the position of the Neutral Start and Back Up switch, check the adjustment of the manual control linkage. (Refer next column for details.)

COLUMN SHIFT:

  1. Place selector lever in 'N' range.
  2. Loosen the two screws securing the switch to the steering column jacket then rotate the switch to a position where it is possible to insert a .092 in. dia. pin into the hole in the back of the switch to a depth of approximately 1/4 inch.
  3. Hold the switch in this position and tighten the switch attaching screws. Remove the pin from the switch.
  4. Check the operation of the neutral start switch. The starter should operate only in 'N' and 'Park'.
  5. Check the operation of the back-up lamp switch by turning the ignition switch 'ON' and move the selector lever through all range positions. The back-up lamps should light only when 'R' is selected.

FLOOR SHIFT:

  1. Place selector lever in 'N' range.
  2. Remove the screw attaching the Tee handle to the selector lever. Remove handle.
  3. Remove the transmission control cover assembly attaching screws, raise cover and remove light socket. Remove cover.
  4. Loosen the two neutral start and back up switch screws.
  5. Rotate the switch to a position where it is possible to insert a .092 in. dia. pin into the hole in the back of the switch to a depth of approximately 1/4 inch.
  6. Hold the switch in this position and tighten the switch attaching screws. Remove pin from switch.
  7. Check the operation of the neutral start switch. The starter should operate only in 'N' and 'P'.
  8. Check the operation of the back-up lamp switch by turning the ignition 'ON' and move the selector lever 'through" all range pnsitions. The back up lamps should light only when 'R' is selected.
  9. Replace cover and 'T' handle.

Manual Control Linkage Adjustment:

FLOOR SHIFT:
   The manual control linkage of both V8 and L6 models with floor shift should be adjusted as follows. Refer Fig. 2.

Loosen the lock screw in the transmission control rod trunnion and set the selector lever in 'Park' position. Move the external control lever on the transmission to 'Park' position and tighten lock screw. to 17-23 lbs. ft. torque

COLUMN SHIFT:   The manual control linkage of both V8 and L6 models with column shift should be adjusted as follows. Refer Fig. 3.

Loosen lock screw on transmission control rod trunnion. With the transmission gate attaching screws loosened and lower lever on column in 'Park' position on gate set indicator dial in 'Park' position and retighten gate attaching screws. With the external control lever on transmission in 'Park' position tighten lock screw to 17-23 lbs. ft. torque.

Loosen lock screw on transmission control rod trunnion. Set lower lever on column in 'PARK' position and transmission external control lever in 'PARK' position. Tighten lock screw on transmission control and trunninn to 17-23 lb. ft. torque. Adjust wire pointer on shift tube to give correct range indication on indicator dial.

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  • Manual Control Linkage AdjustmentManual Control Linkage Adjustment
    Lingage Adjustment

FIG. 2

Detent Actuating Switch Adjustment:   Detent valve movement is controlled by the action of a solenoid within the transmission. The solenoid is actuated by a switch as the throttle linkage reaches wide open position. The switch is located on a bracket integral with the accelerator pedal mounting on the inside of the firewall.

Before carrying out the adjustment of the detent switch. it is essential that the throttle control linkage is correctly adjusted.

The switch should be adjusted as follows:

  1. Slacken the lock nut and screw the switch out one turn Fig. 4.
  2. Disconnect the switch cable from the solenoid connector tenninal at the transmission and connect a 12 volt test light between the cable terminal and a good earth on the transmission.
  3. With the ignition "ON" and floor covering in place, depress the accelerator pedal to the floor.
  4. Screw switch in until test light comes on and tighten lock nut.
    NOTE: The switch must not he screwed to more than half a turn past light illumination point.
  5. Remove test light and reconnect switch cable to solenoid connector terminal.

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  • Detent Actuating SwitchDetent Actuating Switch
    Detent Actuating Switch

FIG. 4

MECHANICAL COMPONENT DESCRlPTlON:

Transmission Case:
   All HQ Trimatic transmissions use the right hand control case for both floor and column shift.

Revisions to the oil passages in the case have been made to accommodate the solenoid controlled detent valve mechanism. (Fig. 5).

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  • Transmission Case Oil PassagesTransmission Case Oil Passages
    Transmission Case Oil Passages

FIG. 5

Torque Converter Assembly:   Transmissions for 202 cu. in. engines use a 10" forward bend torque converter which is identified by a cross of green paint.

Input Shaft:   A spigot is machined on the front of the input shaft of L6 Trimatics to support the forward end of the shaft in a bush retained in the converter cover. In V8 applications the input shaft has no spigot and is supported by the converter turbine hub which runs in a bush in the convertor cover (Fig. 6).

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  • Input Shaft and Turbine Hub - V8Input Shaft and Turbine Hub - V8
    Input Shaft and Turbine Hub - V8

FIG. 6

Servo Piston Return Spring:   Three different servo piston return springs arc used in Trimatic transmissions for HQ models as follows:

TRANSMISSION CODE
SPRING COLOUR IDENTIFICATION
HT (202)
Brown
HN (173)
None
HO & HP (253 & 308)
Violet

Gear Set:   The gear set used in Trimatic transmissions for the HQ series differs for those used in previous Trimatics in a number of respects.

No attempt should be made to mix HQ type gears with components for previously used gear sets and it is not possible to build HQ type gears into earlier planet carriers.

NOTE: The term "gear set" refers collectively to the input and reaction sun gears with their associated hub or drum, the ring gear, the planet carrier with output shaft, the long and short planet pinions with their shafts, roller bearings and thust washers.

HQ type gear set components may be identified as follows.

DESCRIPTION
No. of TEETH
IDENTIFICATION
Ring Gear
74
2 Grooves on O.D. of gear
Input sun gear assembly
26
2 circumferential grooves on teeth
Reaction sun gear and drum assembly
34
2 circumferential grooves on teeth
Long pinions
20
2 circumferential grooves on teeth
Short pinions
15
2 circumferential grooves on teeth
Washer - short pinion thrust (steel)
8 per
.84 inch O.D.
Washer - short pinion thrust (bronze)
8 per
.84 inch O.D.
Planet carrier assembly
- - -
Larger opening in carrier front plate for input sun gear (1.840 inch dia. compared with 1.785 inch dia. in previously used carriers).

NOTE: Refer "Overhauling Unit Assemblies" for details of correct gear orientation during planet carrier reassembly.

Clutches:   Second Clutch. HP (308) transmissions use 6 drive plates and 7 driven plates with a spacer 1.407 to 1.403 inches long.

Third Clutch. HO (253) transmissions use 4 drive and 5 driven plates with an L6 type piston (.779 to .775 inches long.)

For full details of HQ Trimatic clutch packs refer "Specifications".

HYDRAULIC COMPONENTS AND OPERATION:

Oil Pump:
   The pressure regulator valve, spring, boost valve and sleeve are retained in the bore of the oil pump by a loose fitting pin in a blind hole. Refer "Overhauling Unit Assemblies"' for disassembly details.

Pressure Regulator Valve & Boost Valve:   All transmission codes use the same type boost valve and sleeve.

Pressure Regulator Valve Spring:   Two different pressure regulator valve springs are used. The HN (173) and HO (253) transmissions use a spring identified with white paint while the spring for HP (308) and HT (202) transmissions has no colour identification. The HN and HO transmissions have a minimum oil pressure of 50 PSI and the HP and HT transmissions have a minimum oil pressure of 60 PSI.

Valve Body:   (Fig. 7) The cast iron valve body is bolted to the under side of the transmission case and contains most of the valves which control transmission operation. A steel transfer plate and gaskets are located between the valve body and case. The valve body contains the 1-2 shift train (Nos 1 thru 5) 2-3 shift train (6 thru 11) the 3-2 control valve, spring and bore plug (16 thru 19), the detent pressure regulator valve and spring (24 thru 26). The manual valve (27), the 1-2 accumulator control valve. 1-2 accumulator valve and bore plug (12 thru 15) the reverse and low control valves and spring (20 thru 23), the low speed downshift timing valve and spring and the high speed downshift timing valve and spring (28 thru 34).

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  • Cross Section of Trimatic TransmissionCross Section of Trimatic Transmission
    Valve Body Components

FIG. 7

Revisions have been made to the oil passages in the valve body to eliminate boosted line pressure in 'S' intermediate range (refer large circled area Fig. 8). Valve bodies incorporating the revised passages can be identified by the letter 'L' cast in the area shown in Fig. 8 and by the radius (Circled), also by Cast Part Number 2822925.

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  • Valve Body Oil PassagesValve Body Oil Passages
    Valve Body Oil Passages

FIG. 8

Valve body application can be identified by the last three digits of the production (not service) part number stamped on the underside of the body on the ground surface adjacent to the accumulator piston pin. This area also carries a letter to indicate the calibration of the valve body. Valve bodies will carry the following identification.

CODE
LAST DIGIT of PRODUCTION P/N
HN (173)
004
HT (202)
128
HO (253)
924
HP (308)
925

Transfer Plate:   The transfer plates and gaskets for all transmissions have been revised to direct oil to the detent solenoid. Two different transfer plates are used. The plate for the HO (253) and HP (308) transmissions have a notch cut in the edge on the same side as the servo piston opening (Fig. 9) where HN and HT transmission transfer plates have no identification. All transmission Codes however use the same type plate to case and plate to valve body gaskets.

Valve Body Reinforcement Plate:   The valve body reinforcement plate has been revised to accommodate the detent valve mechanism.

Vacuum Modulator Valve and Sleeve:   There are three different modulator valves and sleeves used in the Trimatic Transmission for HQ series vehicles. The three valves and sleeves are basicallv similar but differ in the valve spool and sleeve bore diameter. Sleeves can be identified by a colour code on the open end and the valves by their different spool diameters, refer Fig. 10.

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  • Identification NotchIdentification Notch
    Identification Notch

FIG. 9

Modulator Valve and Sleeve Identification:   

TRANSMISSION CODE COLOUR (SLEEVE) VALVE SPOOL DIAMTERS
Dia. A Dia. B
HN(173) & HT(202) None .4055 / .4052 .4920 / .4917
HO (253) Blue .3715 / .3718 .4845 / .4848
HP (308) Red .3715 / .3718 .5254 / .5257

1-2 Shift Valve Train:   There are three different 1-2 shift control valves and sleeves used in the Trimatic for HQ series vehicles. There are dimensional differences between the valves and this has required revisions to the sleeves. Refer fig. 11 for identification details of the valves. The sleeves can be identified as follows:

TRANSMISSION CODE
IDENTIFICATION
HT (202)
Flat on closed end of sleeve
HN (173)
None
HO & HP (253 & 308)
Orange colour identification on closed end of sleeve.

A 1-2 shift control valve return spring is used on HT (202) transmissions.

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  • 1-2 Shift Control Valve Identification1-2 Shift Control Valve Identification
    1-2 Shift Control Valve Identification

FIG. 11

Code HN (173):   The operation of the 1-2 shift valve train for code HN transmissions is as described in the Trimatic Automatic Transmission Shop Manual.

Code HT (202) - Downshifted Position:   With the 1-2 shift train in the downshifted position, drive oil is prevented from passing through the shift valve and 2nd clutch passage is open to exhaust. Modulator pressure together with the return spring acts on the left hand end of the control valve, modulator pressure is also directed through the "U" shaped passage to the area between the second and third spools of the control valve. Refer FIG. 12.

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  • 1-2 Shift Train Downshifted - Code HT Transmissions1-2 Shift Train Downshifted - Code HT Transmissions
    1-2 Shift Train Downshifted - Code HT Transmissions

FIG. 12

Upshifted Position:   When governor pressure nloves the shift train to the upshifted position, the 2nd clutch exhaust is closed and drive oil passes through the shift valve to apply the 2nd clutch. 1-2 control valve movement has closed the feed of modulator pressure to the left hand spool of the control valve and opened this area and the "U" shaped passage to exhaust via the detent passage. The only downshifting force on the valve train will then be the shift valve and shift control valve springs. Under these conditions no part throttle shift to Ist gear is possible.

Normal closed throttle downshifts to 1st gear will occur as the vehicle is brought to a stop. Refer FIG 13.

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  • 1-2 Shift Train Upshifted - Code HT Transmissions1-2 Shift Train Upshifted - Code HT Transmissions
    1-2 Shift Train Upshifted - Code HT Transmissions

FIG. 13

NOTE: Modulator pressure between the second and third spools of the control valve wiIl have no effect on the shift pattern since the spools have equal areas.

Detent 3-1 Shift:   Although the part throttle shift to 1st gear is not available on Code HT Trimatics. a detent 3-1 is still possible (Refer Fig. 13). At full throttle, detent regulator pressure is directed via the detent passage to act on the area difference between the first and second spools of the control valve and also on the left hand spool via the "U" shaped passage. Detent regulator pressure plus spring force will overcome governor pressure and move the shift train to the 1st gear position provided road speed is below the maximum 3-1 shift point. Operation of the valve train in ''L'' range is as described in the Trimatic Shop Manual.

Codes HO (253) & HP (308) - Downshifted Position (FIG. 14):   With the vehicle operating under light throttle, modulator pressure on the end spool of the shift control valve is insufficient to move the control valve against the force of the shift valve spring. Under these conditions the spring is the only force opposing governor pressure on the shift valve.

Drive oil is blocked by the shift valve and the second clutch circuit is open to exhaust.

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  • 1-2 Shift Train Downshifted - Code HO and HP Transmissions1-2 Shift Train Downshifted - Code HO and HP Transmissions
    1-2 Shift Train Downshifted - Code HO and HP Transmissions

FIG. 14

Under slightly wider throttle opening, with modulator pressure greater than approximately 15 p.s.i. the force on the end of the control valve will have become great enough to overcome the shift valve spring and move the control valve against the shift valve and allow modulator pressure to operate on the area difference between the 2nd and 3rd spools of the control valve (Fig. 15). Under these conditions the shift valve spring ceases to provide any opposition to governor pressure on the shift valve and modulator pressure on the two locations nf the control valve is the only force opposing governor.

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  • 1-2 Shift Train Downshifted - Code HO and HP Transmissions - Greater than 15 p.s.i. Mod. Pressure1-2 Shift Train Downshifted - Code HO and HP Transmissions - Greater than 15 p.s.i. Mod. Pressure
    1-2 Shift Train Downshifted - Code HO and HP Transmissions - Greater than 15 p.s.i. Mod. Pressure

FIG. 15

This two stage control of the 1-2 shift train is necessary to provide the desired 1-2 shift points under light throttle operation.

As vehicle speed and governor pressure increase, a force is developed on the end of the shift valve opposing modulator pressure on the control valve. When the force resulting from governor pressure becomes great enough to overcome modulalor pressure, the shift train moves to the upshifted position. Shift valve movement closes the exhaust port and opens the second clutch circuit to drive oil to apply the second clutch. Second clutch oil is also directed to rest on the 2-3 shift valve.

To prevent any tendency for the valve train to "hunt" during the shift, line pressure acts on a difference in area between the spools of the shift valve.

An additional force assisting this snap action is obtained by modulator pressure at the second spool of the control valve being cut off as the valve train moves. The oil in this pocket is exhausted through the detent passage.

If manual low range is selected, line pressure is supplied from the manual valve via the "Low" passage to the pocket between the shift and shift control valves.

Since line pressure can never be less than governor, the force established by line pressure on the shift valve plus spring force will move the valve to the downshifted position regardless of vehicle speed and lock the transmission in first gear.

2-3 Shift Valve Train:   Two different 2-3 shift control valves and sleeves are used in the Trimatics for HQ sedes vehicles. The valves are basically similar but differ in spool diameters which requires corresponding changes in sleeve bore diameters. Sleeves for V8 engine applications (codes HO & HP) are colour coded yellow for identification on the closed end of the sleeve. For valve identification details Refer Fig. 16.

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  • 2-3 Shift Control Valve Identification2-3 Shift Control Valve Identification
    2-3 Shift Control Valve Identification

FIG. 16

INSERT TABLE HERE

Detent Valve Assembly:   The detent valve assembly consists of the detent valve, sleeve and spring. The assembly is retained by a pin in a bore at the rear of the transmission case and sealed by an "O" ring on the sleeve.

Detent valve movement is controlled by the spring detent regulator pressure and the action of an electric solenoid within the transmission. The solenoid, which incorporates a needle valve is actuated by a throttle linkage controlled switch.

Operation: (FIG. 17)   When the engine is running, detent regulator pressure is directed via a restriction to a cavity in the case to act on the end of the detent valve and on the needle valve of the solenoid. During normal throttle operation the cavity is sealed by the needle valve.

With the throttle linkage at any position but full throttle, detent regulator pressure keeps the detent value bottomed in its sleeve against the force of the spring. With the valve in this position, detent regulator pressure is blocked by a spool of the valve from entering the detent passage.

When the throttle is opened wide, (Fig. 18) the switch on the throttle linkage is closed, this energizes the solenoid. The needle valve is opened by the solenoid, allowing detent regulator pressure in the cavity at the end of the Detent Valve to drop. The spring moves the valve to block modulator oil and permit detent regulator pressure to pass through the valve to the 1-2 and 2-3 shift control valves and 3-2 control valve via the detent and modulator passages to initiate the shift to 2nd or 1st gear depending on road speed.